People will mine whatever turns a profit. The market will determine what currency succeeds.

I just don't see how we can put buying/investing pressure on people if we don't have some sort of incentive to spend.

The only way to put pressure is either by printing more money (inflation) or giving a cut of lost/stored coins right back into the miners pockets (demmurage). I must admit this concept of demmurage on a digital currency is a radically different concept. Normally when people talk about demmurage they are talking about giving money to a "third" party to keep their money safe from going missing. Instead of giving this money to the banks/stores/and any other third party entity, with a demmuragecoin we would be giving the money right back to the miners, literally fueling our economy, and never loosing a single coin.

And in the end it will still have the deflationary properties of Bitcoins that people seem to love so much, but it will come with a price.

In the past two months there have been 15 reorgs of the blockexplorer.com data-collection node. Assuming that a fork of the block chain resulted in only two branches, and that blockexplorer.com had just a 50% chance of selecting the “correct” branch, that means there has been 30 forks of the block chain in the last two months. That's 30 out of 8928 blocks for July and August, or about 0.336% chance for a given block. Now assuming that the network was not subject to malicious action during this time*, that means that in those 30 instances two blocks were generated close enough in time to be within the network latency. Or put differently, we can calculate the network latency of the current, existing bitcoin network to be: 10min/0.336% = 2.02 seconds.

*If it was, that would only lower the resulting latency.

Extrapolating into the future, we can expect this number to go down, not up. That may be somewhat counter-intuitive, but what we are seeing now is the worst-case possibility. The bitcoin peer-to-peer overlay is not optimized, at all. It is also conceivable that when a crypto-currency goes mainstream, we may see the emergence of fiber-optically connected payment processing nodes that can relay blocks and transactions to disparate parts of the network very quickly.

Further, it's not very clear that an increase in the number of forks would even been an issue. Bitcoin has defenses built into the protocol for resolving such conflicts. It is only when the probability of a split exceeds 50% that the block chain becomes divergent. On the current bitcoin network, that means round times must be no shorter than 4 seconds.

10 seconds is more than twice that lower limit, and as I said that limit will only get *smaller* as the network gets smarter.